Abstract: The method of this invention comprises an efficient technique for transfer of information over a communication link between first and second processors, the processors employing blocks of data on a repetitive basis. Each processor includes means for storing copies of used blocks of data. A block of data currently used (or displayed) in the second processor is called an "old" data block and a block of data to be transmitted from the first processor to the second processor is called "new" data block. The method includes the steps of storing identical copies of used data blocks and the old data block in the memories of the first and second processors. The new data block is then compared in the first processor to stored data block copies to determine if the new data block equals a pre-established level of similarity with any of the stored data block copies.